Lightweight roll construction

ABSTRACT

The specification discloses a lightweight construction for rolls of the composite type employed in corrosive environments and other environments in which minimal weight or low inertia is a favorable factor. Various constructions are disclosed comprising a central core or shaft of fiber glass reinforced plastic or of steel having a protective coating or layer of fiber glass reinforced plastic, and a body of syntactic foam molded into a cylindrical form coaxial to the shaft and bonded thereto. A layer of fiber glass reinforced plastic surrounds the outer cylindrical surface of the body of foam and protects the annular ends of the roll. An outer abrasion protecting layer of elastomer material is bonded or otherwise secured to the outer cylindrical surface of the fiber glass plastic layer. The syntactic foam comprises nodules or spheres of glass, epoxy or phenolic material suspended in a matrix of thermosetting resin, in various degrees of density. One arrangement employs a matrix consisting of thermosetting resin and microspheres of glass, epoxy, phenolic or other material. Another arrangement employs a matrix of thermosetting resin with other reinforcing agents such as fibers of glass, boron, graphite, steel or asbestos. A further variation employs a matrix in which a blowing agent, such as azodicarbonomide is introduced into a thermosetting resin with an activator such as oxalic or acetic acid.

United States Patent Walls 51 May 16,1972

[54] LIGHTWEIGHT ROLL CONSTRUCTION Harold D. Walls, White Twsp. Cty. oflnd., Pa.

McCreary Industrial Products Co., Indiana, Pa.

[22] Filed: Feb. 25, 1971 [21] Appl.No.: 118,907

[72] Inventor:

[73] Assignee:

FOREIGN PATENTS OR APPLICATIONS 288,851 1/1967 Australia ..29/l32191,613 1/1923 GreatBritain ..29/l30 Primary Examiner-Alfred R. GuestAttorneyBuell, Blenko & Ziesenheim [5 7] ABSTRACT The specificationdiscloses a lightweight construction for rolls of the composite typeemployed in corrosive environments and other environments in whichminimal weight or low inertia is a favorable factor. Variousconstructions are disclosed comprising a central core or shaft of fiberglass reinforced plastic or of steel having a protective coating orlayer of fiber glass reinforced plastic, and a body of syntactic foammolded into a cylindrical form coaxial to the shaft and bonded thereto.A layer of fiber glass reinforced plastic surrounds the outercylindrical surface of the body of foam and protects the annular ends ofthe roll. An outer abrasion protecting layer of elastomer material isbonded or otherwise secured to the outer cylindrical surface of thefiber glass plastic layer. The syntactic foam comprises nodules orspheres of glass, epoxy or phenolic material suspended in a matrix ofthermosetting resin, in various degrees of density. One arrangementemploys a matrix consisting of thermosetting resin and microspheres ofglass, epoxy, phenolic or other material. Another arrangement employs amatrix of thermosetting resin with other reinforcing agents such asfibers of glass, boron, graphite, steel or asbestos. A further variationemploys a matrix in which a blowing agent, such as azodicarbonomide isintroduced into a thermosetting resin with an activator such as oxalicor acetic acid.

10 Claims, 8 Drawing Figures F1 I I PNENTEUHAY 16 I972 3, 662 446INVENTOR Harold D. Walls LIGHTWEIGHT ROLL CONSTRUCTION Rolls of the typecommonly and widely used in steel fabricating, paper making and otherindustries are subject to corrosive environments as a result of the useof various strong pickling or cleaning agents employed in themanufacturing process. I-leretofore, rolls commonly employed in theseindustries consisted of hollow steel cylinders supported on steel shaftsand coated with corrosion resistant material such as neoprene,acid-resistant rubber or other elastomeric material. While initiallysatisfactory for the purpose intended, rolls so coated unavoidablysustain damage to the neoprene coating which results in rupture of thecoating and consequent access of the acid to the steel core of the roll.While there is a possibility of repair if detected soon enough, itfrequently happens that the rolls are damaged beyond repair before thefailure of the coating is detected.

Improved composite rolls have been proposed as for example that made inaccordance with the process described and claimed in US. Pat. No.3,520,747 to Robert S. McGaughey,

assigned to the assignee of this invention. Such improved rolls provideon the core of steel or other structural material a corrosion resistantresin material reinforced with a mat or cloth of fibrous material, suchas fiber glass, polyvinyl type fibers such as Dynel (polyvinyl chlorideacrylonitrile copolymer), Orlon (polyacrylonitrile), polyester fibersuch as Dacron, polyamide fiber such as nylon, or naturally occuringfibers such as asbestos and crocodilite (blue asbestos). A resilientelastomeric layer is bonded to the outer surface of the roll to provideadditional abrasion resistant protection.

More recently an improved roll construction of lightweight constructioncompared to prior known rolls has been proposed, as disclosed andclaimed in the copending application Ser. No. 771,407, filed Oct. 29,1968 by Leonard S. Meyer and assigned to the assignee of this invention.The roll construction of the said application employs a reinforcedcylindrical plastic shell structure supported on a coaxial core or shaftby annular end discs and one or more intervening axially spaced discs orbulkheads providing longitudinal support for the cylindrical plasticshell. With such construction, however, the outer cylindrical shell mustof necessity be suffciently thick to provide rigidity of thelongitudinal sections bridging the axially spaced bulkheads or thebulkheads must be sufficiently closely spaced to provide longitudinalsupport for the cylindrical shell. In either case, the weight of thematerials becomes a factor. Also, such rolls have a tendency to fill upwith a processing fluid from an industrial processing line, in the eventthat some structural damage to the roll occurs which exposes theinterior of the roll to such fluid. Moreover, the required assembly ofmultiple components and the relative complexity of the process ofmanufacture result in an unfavorably high cost ofmanufacture.

It is accordingly an object of the invention to obviate some of thedisadvantages of the heretofore known rolls of the composite type, andto provide a lightweight roll construction of relative simplicity andlow-cost for use in corrosive environments and in other environments andindustries, such as aluminum and copper foil processing wherelightweight and low inertia of the roll are favorable factors to beconsidered.

In the accomplishment of the above object there is provided, inaccordance with the invention, an improved lightweight roll constructionemploying a shaft or core of steel covered with a coating of fiber glassreinforced plastic, or a shaft wholly constituted of fiber glassreinforced plastic or other material structurally sufficient in strengthto withstand the physical loads imposed thereon, surrounded by a body ofsyntactic foam which is bonded to the shaft and molded in the form of acylinder coaxial to the shaft. The body of foam is, in turn, surroundedby a layer of fiber glass reinforced plastic bonded thereto, and anabrasion resistant covering of elastomeric material is bonded to theouter cylindrical surface of the fiber glass reinforced plastic layer.The syntactic foam comprises nodules or spheres of glass, epoxy, orphenolic material suspended or mixed in a matrix of thermosetting resinin different selected degrees of density, depending on the environmentin which the roll is to be used. One form of syntactic foam providedemploys a matrix for the nodules consisting of a thermosetting resin andmicrospheres of glass, epoxy, phenolic, or other material. A variantform of foam provided employs a matrix consisting of a thermosettingresin having reinforcing agents, such as fibers of glass, boron,graphite, steel or asbestos. In another form of syntactic or compositefoam, there is provided a blowing agent, such as azodicarbonomide,introduced into a thermosetting resin together with an activator such asoxalic or acetic acid. Alternatively, the matrix of integral foam may bea commercial foam system such as a polyol-diisocyanate blend whichreacts to form an integral urethane foam.

The above objects, features and advantages of the invention, togetherwith structural details thereof, will be elaborated upon in theforthcoming description of presently preferred embodiments of theinvention, together with preferred methods for constructing the same.

In the accompanying drawings:

FIG. 1 is a fragmented elevational view, partially in section, showingone embodiment of the invention;

FIG. 2 is a fragmented elevational view, partially in section, showing amodification of the embodiment shown in FIG. 1;

FIG. 3 is a fragmental enlarged view of a portion of the roll as shownin either FIG. 1 or FIG. 2, depicting the detailed composition of oneform of syntactic foam used therein;

FIG. 4 is a fragmental enlarged view of a portion of the roll as shownin either FIG. 1 or FIG. 2, depicting the detailed composition ofanother form of syntactic foam used therein;

FIG. 5 is a fragmental enlarged view of a portion of the roll as shownin either FIG. I or FIG. 2, and representing the detailed composition ofanother form of syntactic foam used therein; and

FIGS. 6, 7 and 8 are fragmental enlarged views of a portion of the rollas shown in either FIG. 1 or FIG. 2, wherein the detailed composition ofother forms of syntactic foam used therein are shown.

Referring to FIG. 1 of the drawings, the roll depicted therein comprisesa shaft 10 of steel or other suitable metal, such as aluminum or bronze,a protective layer 11 of fiber glass reinforced plastic covering andbonded to the steel shaft, a body of syntactic or composite foam I2surrounding and bonded to the protective layer 11 on the shaft, and aprotective layer 13 of fiber glass reinforced plastic enclosing the bodyof foam and bonded to the foam as well as to the protective layer 11 onthe shaft. An elastomeric layer 14 is bonded to the outside surface oflayer 13 to provide protection against abrasion.

The protective layer 11 bonded to the shaft 10 is preferably of theorder of one-eighth inch thickness. The protective layer 13 for the bodyof foam is preferably of the order of onequarter inch thickness.

Referring to FIG. 2, the modification shown therein differs from that ofFIG. 1, in that a shaft 11' wholly of fiber glass reinforced plastic andwithout a steel core is provided. In this instance the body of foam 12'and the protective layer 13' therefor are both bonded directly to theshaft 11' instead of to the protective layer, as in the embodiment ofFIG. 1. Shaft l l may be solid, as shown, or tubular if desired.

Referring now to FIGS. 3, 4 and 5, three different types of syntacticfoam 12 are depicted respectively therein, differing essentially in thedegree of density of one of the essential components, namely the basicnodule or sphere 15, as will be hereafter explained. The nodules 15 aremade of some element suitable in strength and corrosion resistance towithstand the physical and chemical environment encountered by the roll,such as glass, epoxy and phenolic material. As an example, cellularglass spheres of foam one thirty-second to threeeighths inch in diametermay be employed. Such spheres may be produced by compacting glass powdertogether with an industrial blowing agent to form solid pellets, thenheating such pellets to release the blowing agent (nitrogen, carbondioxide or water vapor) while at the same time fusing together theparticles of glass powder. The resulting glass nodules possess theinherent structural advantages of a spherical shape as well as theadvantage of resistance to chemical action.

In FIGS. 3, 4 and 5, the syntactic foam 12 comprises nodules 15suspended, supported, or mixed in a matrix of thermosetting resin. Anyof the resins selected from the group of polyester, epoxy, phenolic orpolyamide resins may be used as a matrix. In FIG. 3, the syntactic foam12 comprises an excess of resin surrounding the nodules 15, that is, alarger proportion of resin in relation to the quantity of the nodules,so that the density of the nodules in the matrix of resin is a minimum.This relatively smaller density of nodules is represented by the greaterspacing between the nodules 15 in FIG. 3, as compared to their densityin FIGS. 4 and 5, wherein the greater density of the nodules isrepresented by the relatively closer spacing and the close physicalcontact of the nodules with one another. The foam 12 of FIG. 3 mightwell be used in rolls wherein the corrosion resistant qualities of theresin are a more important consideration than the light-weight orlowcost of the glass nodules.

The foam 12 of FIG. 4 represents a syntactic foam wherein the nodulesare compacted into close contact with one another and the proportion ofresin content is just sufficient to fill the spaces between the nodules.

The foam of FIG. represents a syntactic foam wherein the proportion ofresin content is just sufficient to provide a coat or layer 16 on eachmodule to act as a binder, thereby leaving void or empty spaces amongthe nodules. Such a foam might well be used where light-weight and/orlow-cost are an important consideration in the end product.

It will be understood that the foam shown in FIG. 4 represents one thatis intermediate in cost, weight and physical strength compared to thefoams respectively shown in FIGS. 3 and 5.

The foam of FIG. 6 is representative of one that may be of lesser weightand cost than those shown in FIGS. 3, 4 and 5. In this form of foam, thenodules having a coating 16 of resin are in close contact with oneanother and the void spaces surrounding the nodules are completely orsubstantially completely filled with so-called microspheres 17 ofrelatively smaller diameter than the nodules 15. In size, microspheres17 may be in the range of 4 to 300 microns in diameter. The microspheresmay be made of the same materials, heretofore mentioned, of which thenodules are made, and, in addition, may be made from saran (vinylidenechloride/acrylonitrile).

In FIG. 7 is shown a representation of a foam comprising nodules l5suspended in a thermosetting resin in proportions, such as depicted inFIGS. 3 or 4, and further including one or more reinforcing agents, suchas fibers 18 of glass, boron, graphite, steel or asbestos.

In FIG. 8 is shown a representation of a foam comprising nodules l5 andmicrospheres l7 suspended in a thermosetting resin matrix in which thereis introduced a blowing agent such as azodicarbonamide with an activatorsuch as oxalic acid or acetic acid. In lieu of the latter form ofmatrix, an alternate matrix may be employed comprising a commercial foamsystem such as a polyol-diisocyanate blend which reacts to form anintegral urethane foam.

A preferred method for processing the component materials into thefinished product of a lightweight roll may be employed as follows:

a. If a steel shaft or core is to be employed, it is first covered witha protecting coating of fiber glass reinforced plastic.

b. The coated shaft, or a shaft made wholly of fiber glass reinforcedplastic, is suitably supported in a vertical position.

c. A wooden disc having a central hole, or other suitable centeringdevice, is slipped over the shaft with the central hole conformingclosely in diameter to that of the shaft and the circumferentialperiphery of the disc being concentric to the shaft. The disc is sopositioned that its upper face provides the molding surface for one endof the roll.

d. A cylindrical sleeve mold of appropriate material closely conforminginternally to the diameter of the disc is slipped over the disc andthereby supported coaxially to the shaft. A second disc conforming tothe first disc may be slipped over the shaft and into the cylindricalsleeve mold at the top end, following the next step No. e), to insureconcentricity of the mold and the shaft. Altematively, the cylindricalsleeve mold may constitute a preformed fiber glass reinforced plasticcylindrical sleeve which then is allowed to remain and provide the outerlayer for the body of syntactic foam.

e. The necessary component materials in the syntactic foam desired areweighed according to the proportions desired, then mixed together andwith the necessary catalyst or catalysts for polymerizing thethermosetting resin, in a low-shear mixer. Following the mixingoperation, the mix of materials is poured into the cylindrical sleevemold to substantially fill it therewith and the top supporting disc isthen inserted over the shaft and into the top end of the cylindricalsleeve mold to maintain concentricity thereof with the shaft.

f. The molding apparatus is then placed in an oven and heated to asufiicient and appropriate temperature to initiate the polymerizationprocess, following which the ap-.

paratus is post-cured in conventional manner. If a separate sleeve moldhas been employed, the resultant molded product is now removed from themold. If a cylindrical sleeve mold of fiber glass reinforced plastic hasbeen employed, the end discs only are removed, thus leaving the moldedproduct with an outer cylindrical layer of fiber glass reinforcedplastic to which the body of syntactic foam is bonded.

g. The next step in the process involves covering the outer surface ofthe molded body of syntactic foam with a layer of fiber glass reinforcedplastic by any suitable heretofore known method. If a cylindrical sleevemold of fiber glass reinforced plastic is employed for the mold, it isnecessary merely to cover the exposed annular ends of the molded body ofsyntactic foam with a layer of fiber glass reinforced plastic in such amanner as to bond to the coated shaft, or to the shaft itself, and tothe cylindrical outer layer of fiber glass reinforced plasticsurrounding the molded body d foam.

. The final step in the process involves the application and bonding ofthe elastomeric layer to the outer cylindrical surface of the fiberglass reinforced plastic layer in a suitable or conventional manner,such as that described in the aforesaid McGaughey US. Pat. No.3,520,747. Any suitable commercially available elastomer may beemployed.

While the above method of producing the final product of a lightweightroll construction has been illustratively described herein, it will beapparent that some variations therein may be resorted to withoutdeparting from the basic procedure.

Iclaim:

1. A roll of lightweight construction for use in a corrosiveenvironment, said roll comprising a shaft having an outer surface layerof fiber glass reinforced plastic, a body of syntactic foam molded in acylindrical form coaxially surrounding said shaft and bonded to saidsurface layer, said outer surface layer underlaying said body andextending therebeyond, a second layer of fiber glass reinforced plasticcovering said body of syntactic foam, and a layer of elastomericmaterial surrounding and bonded to said second layer of fiber glassreinforced plastic.

2. A roll according to claim 1, wherein said body of syntactic foamcomprises a mix of nodules in a matrix of thermosetting resin, saidnodules being of a material selected from the group of glass, epoxy orphenolic material.

3. A roll according to claim 1, wherein said body of syntactic foamcomprises nodules suspended in a matrix of thermosetting resin, saidnodules being of a material selected from the group of glass, epoxy orphenolic material.

4. A roll according to claim 1, wherein said body of syntactic foamcomprises nodules in closely compacted contact and surrounded by amatrix of thermosetting resin, said nodules being of a material selectedfrom the group of glass, epoxy or phenolic material.

5. A roll according to claim 1, wherein said body of syntactic foamcomprises nodules in closely compacted contact with one another andindividually coated with a layer of thermosetting resin, said nodulesbeing of a material selected from the group of glass, epoxy or phenolicmaterial.

6. A roll according to claim 1, wherein said body of syntactic foamcomprises nodules made of a material selected from the group of glass,epoxy or phenolic material and ranging in diameter from onethirty-second to three-eighths inch, said nodules being in closelycompacted contact with one another and individually coated with a layerof thermosetting resin and with void spaces interspersed thereamong, andmicrospheres substantially filling the said void spaces and being madeof a material selected from the group of glass, epoxy or phenolicmaterial and ranging in diameter from 4 to 300 microns.

7. A roll according to claim 1, wherein said body of syntactic foamcomprises nodules in a matrix of thermosetting resin, said nodules beingof a material selected from the group of glass, epoxy or phenolicmaterial, and said resin containing a reinforcing agent selected from agroup of materials comprising fibers of glass, boron, graphite, steel orasbestos.

8. A roll according to claim 1, wherein said body of syntactic foamcomprises nodules and microspheres closely compacted in a thermosettingresin matrix containing a blowing agent with an activator.

9. A roll according to claim 1, wherein said body of syntactic foamcomprises nodules and microspheres closely compacted in a thermosettingresin matrix containing azodicarbonamide and an activator selected froma group comprising oxalic acid or acetic acid.

10. A roll according to claim 1, wherein said body ofsyntactic foamcomprises nodules and microspheres closely compacted in a matrix foamsystem comprising a polyol-diisocyanate blend which reacts to form aintegral urethane foam.

2. A roll according to claim 1, wherein said body of syntactic foamcomprises a mix of nodules in a matrix of thermosetting resin, saidnodules being of a material selected from the group of glass, epoxy orphenolic material.
 3. A roll according to claim 1, wherein said body ofsyntactic foam comprises nodules suspended in a matrix of thermosettingresin, said nodules being of a material selected from the group ofglass, epoxy or phenolic material.
 4. A roll according to claim 1,wherein said body of syntactic foam comprises nodules in closelycompacted contact and surrounded by a matrix of thermosetting resin,said nodules being of a material selected from the group of glass, epoxyor phenolic material.
 5. A roll according to claim 1, wherein said bodyof syntactic foam comprises nodules in closely compacted contact withone another and individually coated with a layer of thermosetting resin,said nodules being of a material selected from the group of glass, epoxyor phenolic material.
 6. A roll according to claim 1, wherein said bodyof syntactic foam comprises nodules made of a material selected from thegroup of glass, epoxy or phenolic material and ranging in diameter fromone thirty-second to three-eighths inch, said nodules being in closelycompacted contact with one another and individually coated with a layerof thermosetting resin and with void spaces interspersed thereamong, andmicrospheres substantially filling the said void spaces and being madeof a material selected from the group of glass, epoxy or phenolicmaterial and ranging in diameter from 4 to 300 microns.
 7. A rollaccording to claim 1, wherein said body of syntactic foam comprisesnoDules in a matrix of thermosetting resin, said nodules being of amaterial selected from the group of glass, epoxy or phenolic material,and said resin containing a reinforcing agent selected from a group ofmaterials comprising fibers of glass, boron, graphite, steel orasbestos.
 8. A roll according to claim 1, wherein said body of syntacticfoam comprises nodules and microspheres closely compacted in athermosetting resin matrix containing a blowing agent with an activator.9. A roll according to claim 1, wherein said body of syntactic foamcomprises nodules and microspheres closely compacted in a thermosettingresin matrix containing azodicarbonamide and an activator selected froma group comprising oxalic acid or acetic acid.
 10. A roll according toclaim 1, wherein said body of syntactic foam comprises nodules andmicrospheres closely compacted in a matrix foam system comprising apolyol-diisocyanate blend which reacts to form a integral urethane foam.